2-Pyrazinecarboxylic acid 1-oxide

Styrylpyrazine 1-oxide (254, R = CH CHPh) gave 2-pyrazinecarboxylic acid 1-oxide (254, R = C02H) (KMn04, dicyclohexyl-18-crown-6, PhH, 20°C, 3 h 49%).1300... [Pg.117]

Chloro-5-methylpyrazine 2-Chloro-6-methylpyrazine 6-Chloro-A,-methyl-2-pyrazinecarboxamidine 6-Chloro-5-methyl-2-pyrazinecarboxylic acid 5-Chloro-6-methyl-2-pyrazinecarboxylic acid 1-oxide... [Pg.393]

The cleavage of fused pyrazines represents an important method of synthesis of substituted pyrazines, particularly pyrazinecarboxylic acids. Pyrazine-2,3-dicarboxylic acid is usually prepared by the permanganate oxidation of either quinoxalines or phenazines. The pyrazine ring resembles the pyridine ring in its stability rather than the other diazines, pyridazine and pyrimidine. Fused systems such as pteridines may easily be converted under either acidic or basic conditions into pyrazine derivatives (Scheme 75). [Pg.190]

The pyrazine ring is stable toward permanganate oxidation, and this explains a variety of pyrazinecarboxylic acids that have been prepared from quinoxalines or benzo-fused quinoxalines. In contrast, alkyl side chains on pyrazines are effectively oxidized by permanganate, selenious acid, selenium dioxide, or dichromate to afford the corresponding carboxylic acids (Section 8.03.7.1). Oxidation of pyrazines with hydrogen peroxide or percarboxylic acids gives pyrazine A -oxides and/or A, A -dioxides (Section 8.03.5.2). [Pg.278]

Azirines are dimerized under various conditions to dihydropyrazines or their dehydrogenated products, namely pyrazines (Section 8.03.9.5). Quinoxalines are oxidized with potassium permanganate to afford 2,3-pyrazinedicarboxylic acids, and pteridines are hydrolyzed to give 3-amino-2-pyrazinecarboxylic acid derivatives. Condensation of 3,4-diamino-l,2,5-thiadiazole 176 with a-diketones produces l,2,5-thiadiazolo[3,4- Jpyrazines 177, which are reduced to provide 2,3-diaminopyrazines 178 (Scheme 51) <1997JCM250>. [Pg.313]

Chemical Name 2-Pyrazinecarboxylic acid, 5-methyl-, 4-oxide... [Pg.70]

Condensation of 1,2-diaminopropane and 2,3-dioxobutane similarly gives 5,6-dihydro-2,3,5-trimethylpyrazine which is oxidized to the corresponding pyrazine in 58% yield by treatment with potassium hydroxide pellets.111 Hydroxypyrazines are very conveniently prepared from a,j8-dicarbonyl compounds and a-amino acid amides [Eq. (1)],30,112 and pyrazinecarboxylic acids have been prepared by condensation of an a,)5-diketone with an a,/ -diaminocarboxylic acid, followed by oxidation (Scheme 2). Thus, condensation of benzil and... [Pg.113]

The greater stability of the pyrazine ring to oxidation compared with that of benzene enables pyrazinecarboxylic acids to be prepared by permanganate oxidation of either quinoxalines or phenazines. The pyrazine ring is more stable than the pyrimidine ring to acid and alkaline hydrolysis. Thus, pteridine is converted into 2-amino-3-formylpyrazine on treatment with dilute sulfuric acid and N-(3-formyl-2-pyrazinyl)formamidine oxime on treatment with sodium carbonate and hydroxylamine (Scheme 11).136 Aminopyrazines and... [Pg.119]

Oxidation of alkyl- or arylpyrazines with dichromate or permanganate yields pyrazinecarboxylic acids. Thus, Beck reported that on heating 2-methylpyrazine with aqueous dichromate and phosphoric acid in an autoclave at 225°-300°, pyrazinecarboxylic acid was obtained in 74% yield.216 Pyrazine-2,5- and -2,6-dicarboxylic acids... [Pg.140]

Pyrazinecarboxylic acid has been obtained by selenious acid oxidation in pyridine of methylpyrazine or aqueous permanganate oxidation of ethylpyrazine, in yields of 64 and 48%, respectively.171,218 It has also been obtained in 70% yield by partial decarboxylation of pyrazine-2,3-dicarboxylic acid on heating in vacuo at 210°.219 Aqueous permanganate oxidation of 2,5-distyrylpyrazine gives the 2,5-dicarboxylic acid.220 Pyrazine-2,5-dicarboxylic acid has also been prepared in 45% yield by direct carboxylation of pyrazine with carbon dioxide at 50 atm pressure at 250° for 3 hours in the presence of a potassium carbonate and calcium fluoride catalyst.221 Pyrazine-tricarboxylic acid (57), obtainable in only very poor yields by oxidation of 2,5-dimethyl-3-ethylpyrazine, is prepared in 87% yield by alkaline permanganate oxidation of 2-(D-arabo)tetrahydroxybutyl-quinoxaline (56).222 Decarboxylation of the tricarboxylic acid by... [Pg.141]

Hydroxymethyl-2(l/7)-pyrazinone 4-oxide (142) gave 6-oxo-l,6-dihydro-2-pyrazinecarboxylic acid 4-oxide (143) ( Ni peroxide , NaOH, H20, 20°C, 4 h 40%).89... [Pg.213]

Acipimox, 5-methyl-2-pyrazinecarboxylic acid 4-oxide, antihyperlipidaemic [51037-30-0],... [Pg.240]

This chapter includes not only nuclear and extranuclear pyrazinecarboxylic acids and anhydrides, but also the related esters, acyl halides, amides, hydrazides, nitriles, aldehydes, ketones, and any of their thio analogues a few rare isothiocyanatopy-razines and pyrazinecarbonitrile oxides are also included. To avoid repetition, interconversions of these pyrazine derivatives are discussed only at the first opportunity for example, the esterification of carboxylic acids is discussed as a reaction of carboxylic acids rather than as a preparative route to carboxylic esters, simply because the section on carboxylic acids precedes that on carboxylic esters. To minimize any confusion, many cross-references have been inserted. [Pg.299]

Several important preparative routes to pyrazinecarboxylic acids have been discussed already by primary synthesis (Chapters 1 and 2), by oxidation of alkylpyrazines (Section 3.2.4.1), by the indirect ( ) oxidation of halogenoalkylpyrazines (end of Section 4.4), and by oxidation ofhydroxyalkylpyrazines (Section 5.2.2). The remaining methods of preparation are indicated in the following classified examples ... [Pg.299]

Methyl-2-pyrazinecarboxamide 4-oxide (10, R = NH2) gave 5-methyl-2-pyrazinecarboxylic acid 4-oxide (10, R = OH) (2.5 M NaOH, reflux, 30 min ... [Pg.301]

Methyl-2-pyrazinecarboxylic acid 4-oxide (35, R = H) gave methyl 5-methyl-2-pyrazinecarboxylate 4-oxide (35, R = Me) (BF3.Et30, MeOH, reflux, 6 h 75%).669... [Pg.305]

The system, 2-pyrazinecarboxylic acid (54) + tetrabutylammonium metavanadate [(Bu4N)V03] + hydrogen peroxide, in acetonitrile at 0°C induced effective oxidation of alkanes or cyclohexane to hydroperoxides, alcohols to aldehydes or ketones, and aromatic hydrocarbons to phenols.11101715... [Pg.308]

Reactions of pyrazinecarbaldehydes already discussed include reduction to hydroxyalkylpyrazines (Section 5.2.1) and oxidation to pyrazinecarboxylic acids (Section 8.1.1) no Cannizzaro disproportionations appear to have been reported recently. [Pg.338]

Amino-2-pyrazinecarboxamide 3-Amino-2-pyrazinecarboxamide methyloxime 3-Amino-2-pyrazinecarboxamide 1-oxide 5-Amino-2-pyrazinecarboxamide 4-oxide 3-Amino-2-pyrazinecarboxamide oxime 3-Amino-2-pyrazinecarboxamidrazone 3-Amino-2-pyrazinecarboxylic acid... [Pg.365]

Amino-2-pyrazinecarboxylic acid 4-oxide 3-Amino-2,6-pyrazinedicarbonitrile... [Pg.366]

Chloro-2-pyrazinecarboxamide 4-oxide 6-Chloro-2-pyrazinecarboxamidrazone 3-Chloro-2-pyrazinecarboxylic acid... [Pg.394]

Dimethylamino-2-pyrazinecarbonitrile 6-Dimethylamino-2-pyrazinecarbonitrile 6-Dimethylamino-2-pyrazinecarboxamide 6-Dimethylamino-2-pyrazinecarboxylic acid 2-Dimethylaminopyrazine 1-oxide 2-Dimethylaminopyrazine 4-oxide 6-Dimethylamino-2,3,5-pyrazinetricarbonitrile 2-Dimethylamino-3,5,6-trifluoropyrazine 2-Dimethylamino-3,5,6-trimethylpyrazine Dimethyl 3,6-bis(methoxycarbonylmethyl)-... [Pg.410]

Ethoxy-2-py razi necarbonitrile 6-Ethoxy-2-pyrazinecarbothioamide 6-Ethoxy-2-pyrazinecarboxamide 6-Ethoxy-2-pyrazinecarboxylic acid 2-Ethoxypyrazine 1,4-dioxide 2-Ethoxypyrazine 4-oxide 5-Ethoxy-2(l /)-pyrazinone... [Pg.419]

Ethylthio-2-pyrazinecarbonitrile 6-Ethylthio-2-pyrazinecarbonitrile 6-Ethylthio-2-pyrazinecarbothioamide 3-Ethylthio-2-pyrazinecarboxamide 6-Ethylthio-2-pyrazinecarboxamide 3-Ethylthio-2-pyrazinecarboxylic acid 6-Ethylthio-2-pyrazinecarboxylic acid 3-Ethylthio-2,5-pyrazinedicarboxamide 2-Ethylthiopyrazine 1-oxide 2-Ethyl-3,5,6-trimethylpyrazine 2-Ethyl-3,5,6-triphenylpyrazine 2-Ethyl-3-vinylpyrazine 2-Ethynyl-3,6-dimethylpyrazine 2-Ethynyl-3-methylpyrazine 2-Fluoro-5,6-dimethoxy-3-methylpyrazine 2- Fluoro- 5,6-dimethoxypyrazine 2-Fluoro-3,6-dimethylpyrazine 2-Fluoro-3-(l-hydroxyethyl)pyrazine 2-Fluoro-3-iodopyrazine 2-Fluoromethyl-5-methyl-3,6-diphenylpyrazine 2- Fluoro- 5-phenylpyrazine 2-Fluoro-3-phenylthiopyrazine... [Pg.423]

Hydroxymethyl-2-pyrazinecarboxylic acid 2-Hydroxymethylpyrazine 4-oxide l-Hydroxy-3-methyl-2(17/)-pyrazinone l-Hydroxy-5-methyl-2(17/)-pyrazinone... [Pg.430]

Methyl 5-amino-2-pyrazinecarboxylate Methyl 6-amino-2-pyrazinecarboxylate Methyl 3-amino-2-pyrazinecarboxylate 4-oxide 3-Methylamino-2-pyrazinecarboxylic acid 6-Methylamino-2-pyrazinecarboxylic acid 2-Methylaminopyrazine 1-oxide 2-Methylaminopyrazine 4-oxide Methyl 6-anilino-3-isopropylideneamino-2-pyrazinecarboxylate Methyl 3-azido-2-pyrazinecarboxylate... [Pg.442]

Methyl-5-oxo-4,5-dihydro-2-pyrazinecarboxylic acid 1 - Methy 1-6-oxo-1,6-dihy dro-2-pyrazinecarboxylic acid 4-oxide... [Pg.447]

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